I like a lot from your original list! Maybe you talk him into Genevieve nickname Evie, so beautiful. Zinnia is great too. Maren is my favorite from the compromise list. I'm think of using it myself for a middle name.

I would avoid names that are too "wordy". It opens the door for a lot of assumptions and judgements, why saddle your child with that? Yes some names that are technically words may work, like colors, but imo some word names just make one think of nothing but the object, and that takes away from the person.

Flannery- I love Flannery O'Connor and I'm guessing this is in honor of her, but I just don't like the sound. However, it may be perfect for you. It would be unisex, non frou frou, and literary. If I knew someone named Flannery, it could grow on me.